JPS60208261A - Thermal head - Google Patents

Abstract

PURPOSE:To attain to enhance printing quality, by shifting the center of the projection provided to the surface of an insulating substrate from that of a resistance heat generator pattern. CONSTITUTION:In a thermal head, a resistance heat generator 3 is provided to a projection 2 so as to shift the center of the pattern thereof from the center axis of the projection 2 to the side of a common electrode 4a and the center of the temp. distribution of a heat generation part is allowed to coincide with the center axis of the projection 2. For example, the projection 2 with a height of 60mum and a width of 700mum of glass glaze is formed to an alumina substrate 1. Next, 9 dots of resistance heat generators 3 each having a 300mum square are formed to the projection 2 so that the center of a pattern is shifted by 20mum from the center axis Y-Y' of the projection to the side of the common electrode 4a. As mentioned above, by shifting the center of the resistance heat generator 3 from the aspect of a dimension from the center axis of the projection to the side of the common electrode in the thermal head, the there is no difference in printing density even when printing is performed in both directions, and the reduction in energy and miniaturization are enabled.

Description

[Detailed description of the invention] (Industrial application field) The present invention can be used for calculators, personal computers, or measurement 1 analysis.

This relates to thermal devices for heat-sensitive recording used in medical equipment, etc.

(Problems with the structure of the conventional example) As shown in FIGS. 1 to 3, one of the thermal heads that has been put to practical use in the past is a projection 2 made of a glass glaze layer on an insulating substrate l. There is one in which a resistance heating element 3 is formed on the protrusion 2, and a common electrode 4a and a separate electrode 4b are provided on both sides. Note that 5 is a lead wire connection portion, and 6 is a wear-resistant film. The protrusions 2 improve the adhesion between the heating element 3 and the thermal paper, and serve as a heat storage layer to efficiently transmit heat to the thermal paper, thereby improving printing quality and reducing energy consumption.

However, when a do is printed back and forth from side to side (bidirectional printing) on this thermal, a difference may appear in the print density. Possible reasons for this are as follows. First, since the main component of the electrode of the heating element is Cu or Au and has good thermal conductivity, a portion of the heat generated in the heating element diffuses toward the substrate through the electrode. In this case, the common electrode 4a ILllI, which has a larger electrode area, diffuses more heat than the individual electrode 4b side, resulting in a lower temperature. In other words, the center of the temperature distribution of the heating element is biased toward the individual electrodes.

Furthermore, in the case of bidirectional printing, as shown in FIG. Since it is shifted from Y' toward the common electrode 4a or the individual electrode 4b, a difference appears in the print density. To solve this problem,
Although it is possible to deepen the notched portion C of the common electrode 4a (in FIG. 1), the area of the common electrode must be increased by that much, which has the disadvantage of increasing the shape of the head.

(Objective of the Invention) The present invention eliminates these conventional drawbacks, and provides a thermal printer that has no difference in print density even when printing in both directions and can be miniaturized. It is.

(Structure of the Invention) The thermal device of the present invention is provided with a resistance heating element such that the center of the ξ turn is offset from the central axis of the protrusion toward the common electrode, and the temperature distribution of the heating element portion is The center of the protrusion is made to coincide with the central axis of the protrusion.

(Description of Embodiments) Hereinafter, one implementation [)+1 of the present invention will be described with reference to the drawings. First, in FIG. 5, a lath glaze protrusion 2 having a height of 60 microns and a width of 700 microns is formed on an alumina substrate I. Next, place the central axis of the protrusion Y - Y on this protrusion 2.
9 dots of 300 micron square resistance heating elements 3 were formed with the center of the P turn shifted by 20 microns from ' to the common voltage +l1da side.

FIG. 4(b) shows the thermal paper 7 in this embodiment.
This shows the contact status of the In this way, the center of the temperature distribution of the heat generating part is made to coincide with the central axis of the protrusion 2, so that the temperature of the contact part with the thermal paper is made equal regardless of the moving direction of the thermal head.

(Effects of the Invention) As described above, in the thermal head of the present invention, since the dimensional center of the resistance heating element is shifted from the center/axis of the protrusion toward the common terminal side, even in the case of bidirectional printing, the print density is There is no difference in energy consumption, low energy consumption, and miniaturization is possible.

[Brief explanation of drawings]

Fig. 1 is a plan view of a conventional thermal head, and Fig. 2 is a plan view of a conventional thermal head.
The same side view and FIG. 3 are the x-x' sectional view of FIG.
The figures show the state of contact between the front and the thermal paper in the case of bidirectional printing. Figure 4(a) is for a conventional thermal head, and Figure 4(b) is for a thermal head according to the present invention. This is the case. FIG. 5 is a cross-sectional view of one embodiment of the present invention. l Alumina substrate, 2... Glass glaze protrusion, 3...
Resistance heating element, 4a/common electrode, 4b...individual electrode, 5
Lead wire connection portion, 6... wear-resistant film, 7... thermal paper. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A thermal head in which a belt-shaped or dot-like projection is provided on the entire surface of an insulating substrate, a quasi-number of resistance heating elements are arranged on the projection, and a common electrode and individual electrodes are provided at both ends of the resistance heating element, respectively. In A, the thermal device is characterized in that the center of the pattern of each of the resistive heating elements is shifted from the central axis of the protrusion toward the common terminal.